A lot of people have asked us what is a good example application for Carloop. We are working on some example apps for sure, but in the meantime, here is a great Wikipedia article that very clearly outlines how to request PIDs from the ECU. It also explains how to read the response and convert them into physical values.
Can you give details on how messages are received? I see that most of the apps follow a similar pattern.
Transmit Query
Go into receive loop for 10ms
I noticed that often no answers come back for my queries especially while the car is off. I can ask for HYBRID_BATTERY_REMAINING every 10seconds for 30-45 mins and receive only one response.